Press roll with tensioned diagonal fabric jacket



July 1, i969 C. SCHIEL 3,452,414

PRESS ROLL WITH TENSIONED DIAGONAL FABRIC JACKET Filed Feb. 2, 1967 Fig.

INVENTOR. CHIMSTIAN SCA-HEL wwww` United States Patent O U.S. Cl. 29--119 10 'Claims ABSTRACT OF THE DISCLOSURE This invention concerns a press roll having a fabric jacket with the threads diagonal to the roll axis and wherein the jacket is tensioned in the axial direction of the roll and the ends of the jacket can turn on the roll as the central region of the jacket s forced circumferentially of the roll during operation of the roll.

Cross reference to a related application This application is based on German application Ser. No. V 30,297 filed Feb. 4, 1966.

Background of the invention The present invention relates to a press roll with a sleeve-like jacket which is mounted on the roll so the threads of the roll are diagonal to the axis of the roll. With a press roll of the nature referred to, the undercloth which moves together with the press felt and the paper web through the press nip, and which consists of a substantially uncompressible fabric, is usually made up of a polymer, and which can be .a knitted material, is in the form of a jacket on the press roll and turns with the roll.

Such fabric jackets, generally speaking, are formed by placing a tubular member of fabric on the roll body and attaching it to the roll. In one of two known processes for mounting such a sleeve on a press roll, the tubular fabric member is manu-factured to a smaller diameter than the roll body, is enlarged under the application of heat, and is then shrunk upon the roll body.

In another procedure, .a tubular fabric member is employed which is larger in diameter than the roll tbody, and which is placed on the roll and then tensioned axially so that it will become elongated in the axial direction and will become narrower thereby in the diameter so that it will make firm contact with the circumference of the roll body. In both cases referred to above, i.e., application by shrinking and the application by tensioning, the two axial ends of the fabric jacket are attached to the roll body so that twisting thereof becomes impossible.

During operation of the roll, forces arise in the press nip, specifically fulling forces due to the crowding of material into the press nip, which try to shift the fabric jacket circumferentially upon the roll body. This will occur with jackets which are shrunk in position on the roll, as well as those which are axially tensioned on the roll.

Most of the material of which the fabric jackets are made, and especially synthetic polymers, such as polyethylene polyamide or polyesters, will show a plastic deformation when under stress, i.e. they will flow somewhat under the fulling forces referred to, and this means that the fabric jacket, which originally fit the roll snugly, will move away from its original position under the action of such forces.

Since the jacket diameter can become reduced only with fabric jackets which have threads running at an angle of 3,452,414 Patented July 1, 1969 inclination to the axis of the press roll, the cover materials for such press rolls comprises the so-called diagonal cloths, namely, cloths which lay on the bias on the roll surface. The present invention contemplates the use of such bias or diagonally laid fabric.

In the usual manner of 'attaching a fabric jacket to a roll, due to the rigid clamping of the two axial ends of a fabric jacket to the roll, only the central region of the jacket can shift on the roll under the circumferential forces referred to. Further, this effect can become quite pronounced. The central threads of the jacket advance on the roll with respect to the edge threads and, in this way, exert a strong pull upon the clamped in end zones of the jacket at the two ends of the roll, and this will often result in a tearing of the fabric and, thus, destruction of the fabric jacket. Particularly in couch rolls and vin dandy rolls, the fabric sleeve will show an advance motion in its center region. One attempt to overcome this diiiculty is shown in the German Patent 137,840 which shows the ends of the jacket or cover retained in position by rings and disks which are arranged to rotate upon the roll or upon the trunnions thereof.

The principle could be applied to the diagonal cloth, except for another complication which arises. The diagonal cloth does not only try to migrate in the circumferential direction, but has, as well, an axial component of motion which imparts to the fabric jacket an additional tendency for a migration in the axial direction of the roll. This comes about ybecause the fabric jacket is essentially supported on the roll surface by crimpings in the warp threads. These crimpings are at an angle to the axrs of the roll and therefore, upon creeping of the jacket, create a motion which has both a circumferential as well as an axial component. The circumferential component of the motion can be in the direction of motion of the roll surface during use as well as against it.

Summary of the invention The present invention seeks to render impossible the shifting, twisting and straining of the fabric jacket upon the press roll due to the fulling which occurs in operatIon so the fabric jacket does not become destroyed so easily. According to the present invention, this problem is solved by supporting the fabric jacket on the roll so that both ends of the jacket are supported moveable circumferentially, and the jacket is clamped down rigidly in the axial direction Vat not more than one end only. On occasion neither end is so clamped. With such jacket mounting, the ends of the jacket can turn freely and, as the central region of the fabric jacket becomes circumferentially shifted under the action of the fulling forces which occur during operation, high strains cannot occur in the fabric jacket between the central region thereof and the ends thereof. The jacket, under the action of these forces is shifted along its full length by substantially the same amount, and therefore, can migrate slowly only around the full roll body. Also the tendency of the jacket to migrate in the axial direction is taken care of in that at not more than one end a rigid attachment of the jacket to the roll in the axial direction is provided. If such a rigid connection is provided, it is placed at the end from which the jacket runs off (run off end). Due to this axial migration of the jacket, the jacket along its full length becomes tensioned by itself on the roll, .and there is no' need to provide a retaining or tensioning device at the other (forward) end.

According to another idea of the invention, however, it is advantageous to keep the fabric resiliently tensioned at the other end in the axial direction, so that the portion of the fabric jacket which protrudes beyond the roll body will not hang loosely. Tensioning of this nature may be accomplished by clamps which attach to the end of the fabric jacket, a ring which may turn freely around the shaft or trunnion of the roll body, and tension springs, connecting the clamps with the retaining ring. In such an arrangement to the natural tension of the fabric jacket the resilient force will be added. The spring force may be adjustable so that there is always imparted to the jacket the desired tension so as to avoid bulges and folds in the fabric, and in this way, to insure a long useful life of the jacket.

According to still another idea of the present invention, the rigid attachment of the fabric jacket to the roll in the axial direction is found at the driving side of the roll. Thus, the forward end of the jacket which, as needed, is resiliently clamped, will be located at the operators side, so that the correct tensioning can easily be supervised by the operator of the machine and, whenever it becomes necessary due to a great elongation of the jacket, the end of the fabric jacket is readily accessible and can become correspondingly shortened.

It also is advantageous according to still another idea of the present invention to attach the fabric jacket to the roll resiliently at both of the ends of the jacket, because then, if the elongation of the jacket becomes too great, the double tensioning reserve will accommodate such change of length.

According to another idea of the present invention, the elasticity constant of the resilient support at the run-off, or driving end of the roll shall be at least one and one-half times as great as the elasticity constant of the support at the forward or operative end of the roll. The axial selftightening force of the jacket and the tensioning force of the resilient attachment will become added to each other at the forward end of the roll, and the spring characteristic of the holder at the run-off end must be correspondingly harder to prevent axial shifting of the entire jacket on the roll.

According to a preferred embodiment of the present invention, the axial forces which exist between the fabric jacket and the body of the press roll, are transmitted therebetween by anti-friction bearings. In this way the friction which arises between jacket and press roll is kept small and free motion of the jacket ends its not preven-ted thereby. Such an anti-friction bearing preferably would, on one side, come to rest against the front side of the press roll, and would also rest against the ring which retains the corresponding end of the fabric jacket.

Brief description of the drawings The exact nature of the present invention will be more fully comprehended upon reference to the following detailed specification, taken together with the accompanying drawings, in which:

FIGURE l shows a press roll, partly in section, with a fabric jacket and holders for the fabric jacket at the ends of the roll, and with one holder or clamp being resilient;

FIGURE 2 is a view like FIGURE 1 but shows an arrangement according to the present invention wherein the holders or clamps at both ends of the fabric jacket are resilient;

FIGURE 3 shows the rigid a-ttachment of the fabric jacket to the holder at the left end of FIGURE 1, and is a section indicated by line III-III on FIGURE 1 and drawn at enlarged scale;

FIGURE 4 shows an end View of the roll looking in from the right end of FIGURE 1 and illustrating the tensioning clamp or holder for the axial tensioning of the fabric jacket; and

FIGURE 5 shows in section and at enlarged scale one of the clamp elements of FIGURE 4 and is indicated byline V-V on FIGURE 4.

In the drawings, fabric jacket 1 in FIGURE l, surrounds the roll body 2, and is clamped in rigidly against axial movement on the roll at one end by wedging the end of the jacket between the two conical rings 3 and 4. Ring 4 is disposed in parallel spaced relation to a raceway 5 which is attached to the adjacent end of the roll. The bearing rollers 6 of an anti-friction bearing which supports ring 4 on raceway 5, are guided inside a cage 7. As will be seen in the drawings, the threads of the fabric jacket are inclined to the direction of the length of the roll.

As shown in FIGURE 3, U-nails 9 driven into spreading bores 10 of the conical ring 3 x the fabric jacket to the ring 3.

Tensioning of the fabric jacket is accomplished by a resilient clamp located at the other end of the roll. As will be seen at the right side of FIG. 1, and in FIG. 4, which is a view looking in at the right end of FIGURE l, the roll body 2 has at each one of its ends a trunnion or journal pin 1.2, 12 and has, furthermore, at the left end in FIGURE l, a driving portion 19 which is rigid with the trunnion 12 and is provided with a keyway 20.

At the right end of the roll body 2, the fabric jacket 1 is held in a resilient manner. At the said right end of the roll body 2, the end of the fabric jacket 1 is guided across a conical ring 4' which is concentric to the roll body. Ring 4 is shaped similarly to ring 4 and, actually, may be completely identical thereto. The ring 4 also rests, with the interposition of an antifriction bearing which is equipped with bearing rolls 6 and a cage 7', against a raceway 5' which is mounted on the adjacent end of roll body 2. This end of `the fabric jacket 1, which is turned around radially towards the center of the roll is attached to clamps 14 arranged radially inwardly from the conical ring 4. FIGURES 4 and 5 show the distribution of the individual clamps 14. A further ring 13', also concentric to the roll body, is located with a small radial play upon the supporting journal 12 of the roll` body 2. Both clamps 14 and ring 13' are equipped with bores for receiving respective ends of tensioning springs 11'. The springs 11 pull the fabric jacket 1 taut, i.e., without any slack, upon the roll body 2, but the fabric jacket remains free from internal stresses and strains even upon the migration of the fabric jacket in the circumferential direction, which is brought about due to the high linear pressures which act inside the slit between the rolls, because the axial ends of the fabric jacket 1, are not impeded by frictional forces, and follow the center part of the jacket as it migrates in the circumferential direction.

The migration of the fabric jacket 1 upon the roll body 2 in the axial direction is prevented by the type of construction by the clamping connection described, i.e., by the presence of the rings 3 and 4 at the left end, and the resilient tensioning at the right end under the action of the -tensioning springs 11.

In contrast to the construction-shown in FIGURES l and 3 wherein one end of the fabric jacket is fixedly held against axial shifting on the roll, the roll according to FIGURE 2 may be constructed at both ends so that in the axial direction a tensioning of the fabric jacket 1 occurs. This tensioning of the jacket 1 is brought about by the aid of radial tensioning springs 11, 11' both at the left as well as at the right end of the roll body.

Springs 11 are connected at their inner ends -to ring 13 which fits over trunnion 12 wtih radial clearance and, at their outer ends, are connected to the adjacent end of jacket 1 by clamps 14 which may be similar to clamps 14, above described.

The springs 11 at the left, and drive, end of the roll away from which the fabric jacket 1 in actual operation will move in the axial direction towards the right, are much stronger than the springs 11' at the opposite, and operators, end of the roll which the fabric jacket 1 approaches when it undergoes a `migration action. To be more specific, the spring constant of the springs 11 is at least one and one half times as great as the spring constant of the springs 11'.

A typical clamp 14 is shown in FIGURE 5 wherein it will be seen that clamp 14 comprises plates 15 and 16 held together and in clamping engagement with the end of jacket 1 by screw 17. Plate 15 has a hole to receive hook 18 on the end of spring 11.

By the described arrangement, the ends of the jacket can follow the central portion of the jacket as the latter migrates circumferentially of the roll during operation. The jacket, of course, normally rotates with the roll :but when the portion of the jacket engaging the circumference of the roll shifts thereon in the circumferential direction, the ends of the jacket readily follow, thus pre` venting straining and distortion of the jacket.

I claim:

1. A cylindrical press roll having ends, a sleeve-like fabric jacket also having ends and closely fitted on the outer periphery of the roll and having its threads ex,- tending diagonally to the direction of the length of ,the roll, the said ends of said jacket extending beyond the said ends of said roll, and clamp means connecting said ends of said jacket to the said ends of the roll, each said clamping means being rotatably supported on the adjacent end of said roll for permitting movement of said ends of said jacket circumferentially of said roll when the portion of said jacket which is between -the ends of said roll shifts circumferentially on the roll.

2. A fabric jacketed press roll according to claim 1 in which not more than one end of said clamp means at one end of said roll clamp-s the adjacent end of said jacket xedly against axial movement on said roll.

3. A fabric jacketed press roll according -to claim 2 in which Ithe end of said jacket at the end of said roll opposite the said one end thereof extends radially inwardly at the pertaining end of the roll and the pertaining clamp means comprises resilient means resiliently restraining said jacket and exerting tension thereon.

4. A fabric jacketed press roll according to claim 3 v in which said clamp means for the end of said jacket which extends radially inwardly at the pertaining end of the roll comprises clamp elements attached to circumferentially spaced points of the radially inwardly extending portion of the said other end of said jacket, said resilient means comprising springs connected to said clamp elements and extending radially inwardly therefrom, and a central ring to which the inner ends of said springs are connected.

5. A fabric jacketed press roll according to claim 2 in which the said one end of said roll at which the end of said jacket is xedly clamped is the driven end of the roll.

6. A fabric jacketed press roll according to claim 1 in which the said clamp means at both ends of said jacket comprise resilient means and exert tension on said jacket.

7. A fabric jacketed press roll according to claim 6 in which one of the said ends of said roll is the driven end and the force of the resilient means at said driven end is about one and one-half times as great as the force of the resilient means at the other end of said roll.

8. A fabric jacketed press roll according to claim 1 which includes antifriction 4bearing means supporting said clamp means on said roll.

A9. A fabric jacketed press roll according to claim 8 in which each said antifriction bearing means comprises an axially inner race means on the pertaining end of the roll, antifriction elements rollingly engaging said race means, and an axially outer race, said outer race having a radially outer portion receiving the pertaining end of the jacket axially outwardly from the adjacent end of the roll and `a radial inner portion which engages said antifriction elements.

10. A fabric jacketed press roll according to claim 9 in which said radially outer portion of said outer race tapers inwardly in a direction away from said roll, and said clamp means including a tapered ring tted on said tapered radially outer portion of said outer roll, said jacket having a portion clamped between said tapered ring and the tapered radially outer portion of said outer race.

References Cited UNITED STATES PATENTS 1,110,397 9/1914 Martini 29-119 1,324,738 12/ 1919 Goedike 29-119 2,704,392 3/ 1955 Schultz 29-119` XR 3,327,369 6/1967 Catlin 29--119 FOREIGN PATENTS 137,84() Germany.

1,304 2/ 1913 Great Britain.

BILLY I. WILHITE, Primary Examiner. 

